Microelectromechanical systems (MEMS) are devices with characteristic dimensions of hundreds of microns or less, which integrate electrical and mechanical elements through microfabrication technology. The electrical and mechanical elements comprise electrically conductive layers on or through which external electrical signals can be applied or delivered such that operations of the electrical and/or mechanical elements can be associated with the external electrical signals. In addition to the electrically conductive layers, insulating materials are often included in the electrical and/or mechanical elements of the MEMS devices for many reasons, such as to improve mechanical properties of the mechanical elements, to prevent unwanted electrical short between the electrical and/or mechanical elements, and to comply with other particular requirements. The insulating material, however, may isolate the electrically conductive layers that are desired to be electrically connected; and in turn bringing about electrical connection difficulties to the MEMS devices.
As a way of example, reflective and deflectable micromirror devices are a type of MEMS device. A typical micromirror device comprises a deflectable and reflective mirror plate attached to a deformable hinge that is held by a post on a substrate such that the mirror plate is capable of being deflected relative to the substrate under an electrostatic force. The electrostatic force is derived from an electrostatic voltage differences between the mirror plate and an addressing electrode associated with and placed proximate to the mirror plate. To enable applications of voltage on the mirror plate, the mirror plate, deformable hinge, and post comprise electrically conductive layers that are desired to be connected together. However, the electrically conductive layers may be electrically isolated by insulating layers that are necessary to comply with specific requirements. For example, an electrically insulating layer may be desired to improve the mechanical properties of the mirror plate, the hinge, and the post. An electrically insulating layer may also be desired to prevent potential diffusion, especially between sacrificial materials and layers of the functional elements of the micromirror device. Because of the electrical isolation of the electrically conductive layers, electrical signals (voltages) are not be able to be delivered to or applied on the target elements, such as the mirror plate of the micromirror devices.
Therefore, what is needed is a method and apparatus for enabling electrical connections between electrical conductive layers that are desired to be electrically connected in the MEMS devices.